Steering rotation angle detecting apparatus of power steering system

摘要

A steering rotation angle detecting apparatus of a power steering having a driving force of a motor applied to a steering pinion shaft via a speed reduction mechanism so as to assist a steering, is disclosed. The steering rotation angle detecting apparatus comprises a steering pinion shaft rotation position detecting means for detecting a rotation position of the steering pinion shaft with respect to a fixed member, a motor phase detecting means for detecting cyclic rotation phase states of the motor, and a steering rotation angle detecting means for detecting an absolute rotation angle over 360 degrees of the steering pinion shaft on the basis of a steering pinion shaft rotation position information detected by the steering pinion shaft rotation position detecting means and a motor phase information detected by the motor phase detecting means. A speed reduction ratio of the speed reduction mechanism is set so that the rotation phase states of the motor at cycles of 360 degrees of the steering pinion shaft rotation position are different.